High-speed mass finishing device and method

ABSTRACT

A vibratory mass finishing machine for faster finishing of parts along with better finishing of the parts (e.g., smoother finishing) compared to the prior art vibratory mass finishing machines. The vibratory mass finishing machine allows the use of a motor with increased horsepower, incorporates a top eccentric weight located at a position below a line defined by a center of mass of the media, and has the top eccentric weight positioned close to a bottom eccentric weight.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to co-pending U.S. Provisional Patent Application No. 61/694,945, filed Aug. 30, 2012, the disclosure of which is hereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

The field of the present invention is drawn to mass finishing machines, especially vibratory finishing machines.

BACKGROUND OF THE INVENTION

Mass finishing is a group of manufacturing processes that allow large quantities of parts to be simultaneously finished. The goal of this type of finishing is to burnish, deburr, clean, radius, de-flash, descale, remove rust, polish, brighten, surface harden, prepare parts for further finishing, or break off die cast runners. The two main types of mass finishing are tumble finishing, also known as barrel finishing, and vibratory finishing. Both involve the use of a cyclical action to create grinding contact between surfaces. Sometimes the workpieces are finished against each other; however, usually a finishing medium is used. Mass finishing can be performed dry or wet, with wet processes having liquid lubricants, cleaners or abrasive, and dry processes not having such materials. Cycle times for running the parts through the finishing machines can be as short as a few minutes or as long as several hours.

Mass finishing processes can be configured as either batch systems, in which batches of workpieces are added, run, and removed before the next batch is run, or as continuous systems in which the workpieces enter at one end of the arrangement and exit at the other end in the finished state. The workpieces may also be sequenced, which involves running the workpieces through multiple different mass finishing processes. In sequential finishing, the finish usually becomes progressively finer.

An example of a prior art finishing machine can be found in U.S. Pat. No. 4,656,718 entitled METHOD OF PRODUCING A FINISHING CHAMBER FOR A VIBRATORY FINISHING MACHINE, the entire contents of which are hereby incorporated herein by reference.

SUMMARY OF THE INVENTION

A vibratory mass finishing machine of the present invention allows for faster finishing of parts along with better finishing of the parts (e.g., smoother finishing) compared to the prior art vibratory mass finishing machines. The vibratory mass finishing machine of the present invention allows the use of a motor with increased horsepower, incorporates a top eccentric weight located at a position below a line defined by a center of mass of the media, and has the top eccentric weight positioned close to a bottom eccentric weight.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a prior art vibratory mass finishing machine.

FIG. 2 is a cross-sectional view of a vibratory mass finishing machine of the present invention.

DETAILED DESCRIPTION

For purposes of description herein, it is to be understood that the invention may assume various alternative orientations, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments of the inventive concepts defined herein. Hence, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered as limiting, unless expressly stated otherwise.

FIG. 1 illustrates a prior art vibratory mass finishing machine 10. The prior art vibratory mass finishing machine 10 is configured to have parts placed therein for finishing. The vibratory mass finishing machine 10 includes a base 12 supporting a vibration assembly 14. The vibration assembly 14 vibrates to cause media 16 to substantially form a torus and move relative to the parts to finish the parts.

The base 12 of the vibratory mass finishing machine 10 includes a substantially hollow, and in the illustrated embodiment cylindrical, housing 18 and a floor panel 20. A plurality of spring mounting brackets 22 extend at a plurality of locations from an interior surface 23 of the housing 18. Each spring mounting bracket 22 supports a spring 24. It is contemplated that any number of spring mounting brackets 22 and springs 24 could be used. For example, 4, 6 or 8 equidistant spring mounting brackets 22 and springs 24 could be used. Each spring mounting bracket 22 includes an angled top plate 26 with a cylindrical spring lower guide 28 on a top surface thereof. A lower end of the spring 24 surrounds the cylindrical spring lower guide 28, with the cylindrical spring lower guide 28 maintaining the spring 24 in a fixed position on the spring mounting bracket 22. The vibration assembly 14 is supported by the springs 24 at tops thereof.

The vibration assembly 14 of the vibratory mass finishing machine 10 is configured to vibrate relative to the base 12. The vibration assembly 14 includes a finishing bowl 30 having a central opening 32 accommodating a center column 34 therein. The finishing bowl 30 includes a substantially vertical outer and upper side wall portion 36 and a lower inwardly curved side wall portion 38 which extends downwardly from upper side wall portion 36. The walls 36 and 38 extend in the illustrated embodiment annularly around the center column 34. A frustoconical gusset 40 extends between the center column 34 and an inner surface 42 of the lower inwardly curved side wall portion 38 of the finishing bowl 30 to form a part and media receiving area 44 which opens upwardly and extends annularly around column 34. Typically, a liner 46 (e.g., elastomeric) is located in the part and media receiving area 44 and adhered to the exterior surface of the center column 34 above the frustoconical gusset 40, on a top surface of the frustoconical gusset 40, on the lower inwardly curved side wall portion 38 of the finishing bowl 30 above the frustoconical gusset 40 and on the inner surface of the substantially vertical outer and upper side wall portion 36. As is well known to those skilled in the art, the liner 46 and the frustoconical gusset 40 can have a plurality of drains (not shown) therein for draining a finishing compound (typically an environmentally-safe, biodegradable liquid which meet most ferrous and nonferrous requirements in deburring, burnishing, cleaning, descaling, radiusing, and rust inhibiting). The part and media receiving area 44 can also include grates over the drains or elsewhere therein for supporting the parts and/or the media to prevent same from falling through the grates.

The vibration assembly 14 includes an eccentric spinning assembly 48 for causing the vibration assembly 14 to vibrate. The eccentric spinning assembly 48 is connected to a top bearing plate 50 and a bottom bearing plate 52 within the interior of the housing 18, with the bottom bearing plate 52 being located at a bottom of the center column 34. The eccentric spinning assembly 48 includes a central tube 54 having a vertical shaft 56 extending vertically therethrough which defines a central axis of rotation 57. A top eccentric weight 58 is connected to a top end of the vertical shaft 56 and a bottom eccentric weight 60 is connected to a bottom end of the vertical shaft 56. Centers of mass of the top eccentric weight 58 and the bottom eccentric weight 60 are both located off of, and in one embodiment the weights 58 and 60 are laterally spaced from, the axis 57 of the vertical shaft 56. As is well known to those skilled in the art, rotation of the vertical shaft 56 having the top eccentric weight 58 and the bottom eccentric weight 60 will cause the vertical shaft 56, and therefore the eccentric spinning assembly 48 and the entire vibration assembly 14 to rotate. It is contemplated that the central tube 54 containing the vertical shaft 56 with the top eccentric weight 58 and the bottom eccentric weight 60 can be inserted into the vibration assembly 14 as a pre-assembled unit, with the central tube 54 having a top bearing 62 connected to the top bearing plate 50 and a bottom bearing 64 connected to the bottom bearing plate 52. Alternatively, the vertical shaft 56 can be directly connected to the top bearing plate 50 and the bottom bearing plate 52 without the central tube 54.

A motor 66 having a rotating output shaft 68 serves to rotate the vertical shaft 56 of the eccentric spinning assembly 48. As illustrated in FIG. 1, the rotating output shaft 68 of the motor 66 has an output wheel 70 thereon and a bottom of the vertical shaft 56 of the eccentric spinning assembly 48 has an input wheel 72 thereon. An endless connector 74 (e.g., belt or chain) extends between the output wheel 70 and the input wheel 72 to transmit rotary motion of the rotating output shaft 68 of the motor 66 to the vertical shaft 56 of the eccentric spinning assembly 48. It is contemplated that the motor 66 can be connected to the base 12 as illustrated in FIG. 1 or can be connected to the center column 34 of the vibration assembly 14.

For several decades, the vertical shaft 56 of the eccentric spinning assembly 48 has been run at a speed of approximately 1200 to 1500 revolutions per minute (RPMs). In this speed range, the media would circle about a center of mass 76 of the media 16 in a circular motion and the media would substantially form a circle 78 as illustrated in FIG. 1. If the vertical shaft 56 was rotated below 1200 RPMs, the media 16 would not move sufficiently against the part to properly finish the part. Further, when the vertical shaft 56 was rotated above 1500 RPMs, the media 16 would move erratically and not in a circle to sufficiently finish the part. In other words, when the vertical shaft 56 was rotated above 1500 RPMs, the “roll” of the media 16 and parts becomes non-uniform and totally unacceptable throughout, with dead spots and/or other variations in the movement of the media 16 and parts. Furthermore, when the vertical shaft 56 was rotated above 1500 RPMs in the prior art vibratory mass finishing machine 10, the vibration assembly 14 would vibrate in a non-uniform manner. The prior art vibratory mass finishing machine 10 has remained substantially unchanged for decades without altering the RPMs of the vertical shaft 56.

FIG. 2 illustrates a cross-sectional view of the vibratory mass finishing machine 10 a of the present invention. Since the vibratory mass finishing machine 10 a of the present invention is similar to the prior art vibratory mass finishing machine 10, similar parts appearing in FIG. 1 and FIG. 2 are represented by the same, corresponding reference number, except for the suffix “a” in the numerals of the latter. The inventive vibratory mass finishing machine 10 a of the present invention allows the vertical shaft 56 a to spin at a speed of between 2000 to 2600 RPMs without encountering any of the undesirable results when the vertical shaft 56 of the prior art vibratory mass finishing machine 10 was run at such speeds. When the vertical shaft 56 a of the vibratory mass finishing machine 10 a spins at 2000 to 2600 RPMs, the media 16 a circles about a center of mass 76 a of the media 16 a in a circular motion, the media 16 a does not move erratically, the “roll” of the media 16 a and parts is uniform and totally acceptable throughout, with no dead spots and/or other variations in the movement of the media 16 a and parts. Such increased speed of the vertical shaft 56 a results in faster finishing of the parts along with better finishing of the parts.

As illustrated in FIG. 2, three changes to the prior art vibratory mass finishing machine 10 allow the inventive vibratory mass finishing machine 10 a to perform better. First, the horsepower of the motor 66 a is increased. The increased horsepower allows the rotating output shaft 68 a of the motor 66 a to spin faster, thereby increasing the speed of the vertical shaft 56 a of the vibratory mass finishing machine 10 a. Second, the position of the top eccentric weight 58 a was moved to a position below a line 100 between the center of mass 76 a of the media 16 a. Third, the top eccentric weight 58 a was moved closer to the bottom eccentric weight 60 a.

FIG. 2 illustrates two measurements that are involved in the inventive vibratory mass finishing machine 10 a. The first measurement is a first distance 150 defined between a point 152 on the circle 78 a of the media 16 a where the media 16 a no longer contacts an inner surface 102 of the liner 46 a of the finishing bowl 30 a during rotation of a top portion of the media 16 a towards the center of the machine and a point 154 where a horizontal line 155 drawn from a center of mass 172 of the bottom eccentric weight 60 a meets the vertical spinning axis 57 a of the vertical shaft 56 a. The second measurement is a second distance 156 between a point 158 where a horizontal line 159 drawn from a center of mass 170 of the top eccentric weight 58 a meets the vertical spinning axis 57 a of the vertical shaft 56 a and the point 154 where the horizontal line 155 drawn from the center of mass 172 of the bottom eccentric weight 60 a meets the vertical spinning axis 57 a of the vertical shaft 56 a. In the vibratory mass finishing machine 10 a of the present invention, a ratio of the first distance 150 to the second distance 156 is between 1.8:1 and 2.3:1, with a preferred ratio of 2:1. With such a ratio, the efficiency of the inventive vibratory mass finishing machine 10 a as described above is met. In the prior art, the ratio of the first distance 150 to the second distance 156 was less than 1.7:1 (see FIG. 1).

Finishing Machines

The present invention is a vibratory finishing machine 10, such as those used for grinding, deburring, descaling, edge-breaking, polishing, bright-honing, burnishing, and any other surface finishing of parts or workpieces, which may, and generally do, be comprised of wood, metal, ceramic, glass, or the like. Such vibratory finishing machines 10 include a finishing bowl 30 having a liner 46 as an elastomer and such elastomer usually has a Shore A Hardness of at least 50, usually 50 to 100, and preferably about 65 to about 90. Further details and characteristics of such elastomeric linings are well known in the art, and reference is made to U.S. Pat. No. 4,162,900, representatively illustrating a vibratory finishing machine embodying a finishing chamber with an elastomeric lining, and U.S. Pat. Nos. 3,161,993; 3,981,693; 3,990,188; 4,012,869; 4,022,012; 4,172,339; 4,177,608; 4,307,544; 4,329,817, and U.S. Pat. No. Re. 27 084, as well as U.S. Pat. No. 4,480,411, for various other types of finishing machines.

Finishing Media

By the term “media” as used herein, or its equivalent terms “finishing media,” “finishing material” or “finishing medium”, it is intended to include loose, comminuted, granular, or particulate, and in any event solid finishing materials of the type presently employed in the trade and others of a similar nature. Although liquid finishing materials or “compound” may also be used in conjunction with solid finishing materials, these are considered to be ancillary, since most finishing processes employ some solid finishing medium. Moreover, the terms first set forth in this paragraph are used generally and herein to designate such solid materials which are used to impart all types of finishes, including those finishes acquired with abrading materials as well as polishing materials and the like, “polishing”, “burnishing”, and so on being terms considered in their usual sense as species of “finishing”. Such suitable finishing media include, inter alia, porcelain, ceramic, aluminum, steel, zinc, stainless steel, and grainite chips, and the like, all as well-known in the art, and in various sizes and configurations, also as well-known in the art, such configurations representatively being cones, bars, cylinders, squares, stars, triangles, wedges, balls, spheres and the like.

Operation

In operation, finishing machines 10 a assembled in accord with FIG. 1 exhibited greatly increased structural stability, with the result that the same mass of finishing media and parts to be finished could be employed in a finishing machine embodying the present invention for an entirely satisfactory finishing operation with a time cycle required for a particular desired finishing effect to be shortened. Additionally, the “roll” of finishing media and parts was uniform and totally acceptable throughout, and no dead spots or other variations in the movement of the mass of finishing media and parts was discernible during a test period of many hours of finishing operations carried out in vibratory finishing machines 10 a according to the present invention. 

1. A vibratory finishing machine for finishing parts comprising: a bowl having a generally circular receiving area for receiving the parts, the receiving area being substantially U-shaped and having an inner wall surface and an outer wall surface; a base having a plurality of movable parts for movably supporting the bowl to allow the bowl to vibrate relative to the base; media in the receiving area and forming a torus when the bowl is vibrated; and an eccentric spinning assembly for causing the bowl to vibrate, the eccentric spinning assembly including a spinning vertical shaft, a top eccentric weight and a bottom eccentric weight, a top weight center of mass of the top eccentric weight and a bottom weight center of mass of the bottom eccentric weight both being located off of a vertical spinning axis of the spinning vertical shaft; the vibratory finishing machine having a first distance between an outermost point of the torus of the media where the media no longer contacts the inner wall surface of the receiving area and a bottom point where a bottom horizontal line drawn from the bottom weight center of mass meets the vertical spinning axis of the spinning vertical shaft; the vibratory finishing machine having a second distance between a top point where a top horizontal line drawn from the top weight center of mass meets the vertical spinning axis of the spinning vertical shaft and the bottom point; and a ratio of the first distance to the second distance being greater or equal to 1.8:1.
 2. The vibratory finishing machine of claim 1, further including: a motor for rotating the spinning vertical shaft.
 3. The vibratory finishing machine of claim 2, wherein: the motor is fixed to the base.
 4. The vibratory finishing machine of claim 2, wherein: the motor includes an output shaft connected to the spinning vertical shaft for rotating the spinning vertical shaft.
 5. The vibratory finishing machine of claim 1, wherein: the movable parts comprise a plurality of springs.
 6. The vibratory finishing machine of claim 1, wherein: the spinning vertical shaft is configured to rotate at 2000 RPMs or greater while maintaining uniform roll of the media.
 7. A method of finishing parts comprising: providing a vibratory finishing machine including a bowl, a base and an eccentric spinning assembly; providing the bowl with a generally circular receiving area for receiving the parts, the receiving area being substantially U-shaped and having an inner wall surface and an outer wall surface; movably supporting the bowl on a plurality of movable parts of the base; placing media and the parts in the receiving area; providing the eccentric spinning assembly with a spinning vertical shaft, a top eccentric weight and a bottom eccentric weight, with a top weight center of mass of the top eccentric weight and a bottom weight center of mass of the bottom eccentric weight both being located off of a vertical spinning axis of the spinning vertical shaft; and rotating the spinning vertical shaft and vibrating the bowl relative to the base to form a torus with the media; the vibratory finishing machine having a first distance between an outermost point of the torus of the media where the media no longer contacts the inner wall surface of the receiving area and a bottom point where a bottom horizontal line drawn from the bottom weight center of mass meets the vertical spinning axis of the spinning vertical shaft; the vibratory finishing machine having a second distance between a top point where a top horizontal line drawn from the top weight center of mass meets the vertical spinning axis of the spinning vertical shaft and the bottom point; and a ratio of the first distance to the second distance being greater or equal to 1.8:1.
 8. The method of finishing parts of claim 7, further including: rotating the spinning vertical shaft with a motor.
 9. The method of finishing parts of claim 8, further including: fixing the motor to the base.
 10. The method of finishing parts of claim 8, further including: connecting an output shaft of the motor to the spinning vertical shaft for rotating the spinning vertical shaft.
 11. The method of finishing parts of claim 7, wherein: the movable parts comprise a plurality of springs.
 12. The method of finishing parts of claim 7, wherein: rotating the spinning vertical shaft includes rotating the spinning vertical shaft at 2000 RPMs or greater; and further including maintaining uniform roll of the media. 